lamp MITSUBISHI LANCER EVOLUTION VI 1999 Owner's Manual

REAR AXLE – Troubleshooting <AYC>27-5
3. INSPECTION CHART FOR DIAGNOSIS CODE
Diagnosis
code No.Diagnosis itemsRef. page
12Power supply voltage (valve power supply) system (open- or short-circuit)27-6
21FR wheel speed sensor system (open- or short-circuit)27-6
22FL wheel speed sensor system (open- or short-circuit)27-6
23RR wheel speed sensor system (open- or short-circuit)27-6
24RL wheel speed sensor system (open- or short-circuit)27-6
25Wrong-diameter tire27-8
26Faulty wheel speed sensor27-9
31Steer sensor (ST-1, ST-2, ST-N) system (open-circuit)27-10
32Steer sensor (ST-N) system (short-circuit)27-10
33Steer sensor (ST-N) system27-11
34Steer sensor (ST-1, ST-2) system (short-circuit)27-11
41TPS system (open- or short-circuit)27-12
51Longitudinal acceleration sensor system (open- or short-circuit)27-12
52Longitudinal acceleration sensor27-13
56Lateral acceleration sensor system (open- or short-circuit)27-12
61Stop lamp switch system (open-circuit)27-13
65ABS monitor system (open-circuit or defective ABS)27-14
71Proportioning valve system (open- or short-circuit)27-14
72Directional control valve (right) system (open- or short-circuit)27-15
73Directional control valve (left) system (open- or short-circuit)27-16
81AYC relay system (open- or short-circuit)27-17
82Electric pump system27-18
83Electric pump system27-19

REAR AXLE – Troubleshooting <AYC>27-8
Code No. 25: Wrong-diameter tireProbable cause
This code is output if the speed of any one of the four wheels exceeds a specified
level with respect to the average of the four wheel speed sensor outputs when the
steering wheel is in the straight-ahead position and the vehicle speed exceeds 20
km/h. At this time, the warning lamp does not light up.
Defective harness or connector

Defective AYC-ECU

Defective ABS-ECU
<Vehicles with ABS>
OK
Replace ABS-ECU.
NG
Check harness between AYC-ECU
and ABS-ECU.NG
Repair
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
NG
Check the following connectors:
B-24, B-95NG
Repair
OK
Check the trouble symptom.
NO
Measure at B-95 AYC-ECU connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Turn tire at 1/2 to 1 revolution/sec.

Voltage across 6/7/8/9 and body
ground.
OK:42 mV or more (when mea-
sured with a circuit tester)
120 mV-P or more (when
measured with an oscillo-
scope)OKCheck the following connector:
B-95
YES
Is ABS diagnosis code No. 15 output?YESGroup 35* – Refer to Troubleshooting
Are correct tires mounted on all four
wheels?NO
Repair
NG
Repair
<Vehicles without ABS>
NO
Repair
NOCheck and repair the harness between
wheel speed sensor and AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connectors:
B-95, B-52, B-17, A-26, A-50, D-04,
D-14, D-19NG
Repair
OK
Check wheel bearing.NG
Replace
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connector:
B-95NG
Repair
OK
Check wheel speed sensor output volt-
age. (Refer to p. 27-37.)NGCheck wheel speed sensor and ABS
rotor. (Refer to Group 35B.)
YES
Check Wheel speed sensor for instal-
lation.NG
Repair
Are correct tires mounted on all four
wheels?
NG
Replace

REAR AXLE – Troubleshooting <AYC>27-9
Code No. 26: Wheel speed sensor system (faulty output
signal)Probable cause
This code is output if the speed of one of the four wheels exceeds a specified level
when the vehicle speed is 20 km/h or more. At this time, the warning lamp is turned
on.
Defective harness or connector

Defective AYC-ECU

Defective ABS-ECU
<Vehicles with ABS>
OK
Replace ABS-ECU.
NG
Check harness between AYC-ECU
and ABS-ECU.NG
Repair
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
NG
Check the following connectors:
B-24, B-95NG
Repair
OK
Check the trouble symptom.
NO
Measure at B-95 AYC-ECU connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Turn tire at 1/2 to 1 revolution/sec.

Voltage across 6/7/8/9 and body
ground.
OK:42 mV or more (when mea-
sured with a circuit tester)
120 mV-P or more (when
measured with an oscillo-
scope)NGCheck the following connector:
B-95
Is ABS diagnosis code No. 15 output?YESRefer to Group 35B – Troubleshooting
NG
Repair
<Vehicles without ABS>
NG
Check and repair the harness between
wheel speed sensor and AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connectors:
B-95, B-52, B-17, A-26, A-50, D-04,
D-14, D-19NG
Repair
OK
Check wheel bearing.NG
Replace
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connector:
B-95NG
Repair
OK
Check wheel speed sensor output volt-
age. (Refer to P.27-37.)NGCheck wheel speed sensor and ABS
rotor. (Refer to Group 35B.)
Check wheel speed sensor for installa-
tion.NG
Repair
NG
Replace

REAR AXLE – Troubleshooting <AYC>27-13
Code No. 52: Longitudinal acceleration sensor systemProbable cause
This code is output when the longitudinal acceleration exceeds a predetermined value
while the vehicle is running with both ABS and brakes being inactive.
Defective longitudinal acceleration sensor

Defective harness or connector

Defective AYC-ECU
NG
Check and repair the harness between
longitudinal acceleration sensor and
AYC-ECU.
OK
Check the trouble symptom.
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connector:
B-95NG
Repair
OK
Measure at B-95 AYC-ECU connector.

Connector connected

Ignition switch: ON

Voltage across 3 and body ground
OK:2.4 V to 2.6 V (where vehicle
in horizontal position)NGCheck the following connectors:
B-95, B-52, D-20
Check the acceleration sensor.
(Refer to P.27-42.)NG
Replace
NG
Repair
Code No. 61: Stop lamp switch systemProbable cause
This code is output under either of the following conditions:

Stop lamp switch remains ON for 15 min. or more.

There is an open-circuit in the harness between AYC-ECU and stop lamp switch.
Defective stop lamp switch

Defective harness or connector

Defective AYC-ECU
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connector:
B-95NG
Repair
OK
Measure at the B-95 AYC-ECU con-
nector.

Disconnect the connector and
measure at the harness side.

Voltage across 11 and body ground

Brake pedal not depressed.
OK:1 V or lessNGCheck and repair the harness between
AYC-ECU and stop lamp switch.
Check the stop lamp switch.NG
Replace

REAR AXLE – Troubleshooting <AYC>27-20
5. INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomInspection
procedure No.Ref. page
Communication between MUT-II and the whole system is not possible.127-20
Communicatio between MUT-II and AYC-ECU is not possible.227-21
AYC warning lamp does not light up when the ignition key is turned to “ON” (engine
stationary).327-22
AYC warning lamp remains lit up after the engine has started.427-23
AYC is inoperative.
Unable to start or accelerate on slippery road surfaces.527-23
Rear tires are noisy during low-speed cornering.
Vehicle skews.627-24
6. INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
INSPECTION PROCEDURE 1
Communication between MUT-II and the whole system is
not possible.
Probable cause
The cause may be a malfunction of the power supply circuit or the ground circuit
of the diagnosis connector.
Defective diagnosis connector

Defective harness or connector
NG
Check and repair the harness between
power supply and diagnosis connector.
OK
Check the trouble symptom.
NG
Check and repair the harness between
body ground and diagnosis connector.
OK
Check the trouble symptom.
OK
Replace MUT-II.
Check the following connectors:
B-22, B-50NG
Repair
OK
Measure at B-22 diagnosis connector.

Disconnect the connector and
measure at the harness side.

Continuity across 4/5 and body
ground
OK:ConductingNG
Measure at B-22 diagnosis combina-
tion meter connector.

Voltage across 16 and body ground
OK:System voltageNGCheck the following connectors:
B-22, B-49, B-75, B-73NG
Repair

REAR AXLE – Troubleshooting <AYC>27-22
INSPECTION PROCEDURE 3
AYC warning lamp does not light up when the ignition key
is turned to “ON” (engine stationary).
Probable cause
The lamp power supply circuit is probably open-circuited, lamp bulb is out, or the
circuit between AYC warning lamp and AYC-ECU or AYC-ECU itself is defective.
Blown fuse

AYC warning lamp out

Defective harness or connector

Defective AYC-ECU
NG
Check and repair the harness between
ignition switch (IG
2) and AYC warning
lamp.
OK
Check the trouble symptom.
OK
Replace combination meter.
NG
Check the harness between AYC
warning lamp and AYC-ECU.NG
Repair
OK
Check the trouble symptom.OK
Replace AYC-ECU.
OK
Check the following connectors:
B-96, B-94, B-08NG
Repair
OK
Measure at B-96 AYC-ECU connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Warning lamp when 36 is grounded
to body
OK:Lit upNGCheck the lamp bulb.NG
Replace
Measure at B-08 combination meter
connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Voltage across 48 and body ground
OK:Symptom voltageNGCheck the following connectors:
B-08, B-74, B-76NG
Repair

REAR AXLE – Troubleshooting <AYC>27-23
INSPECTION PROCEDURE 4
AYC warning lamp remains lit up after the engine has
started.
Probable cause
The AYC warning lamp ON circuit is probably short-circuited.
Defective combination meter

Defective harness (short-circuit)

Defective AYC-ECU
NOTE
This symptom is limited only when the communication with MUT-II is possible with AYC-ECU power supply
in normal condition and the diagnosis code is correct.
OK
Replace combination meter.
NO
Check the harness between AYC
warning lamp and AYC-ECU.NG
Repair
Does the AYC warning lamp goes out
when the B-96 AYC-ECU connector
is disconnected?YESReplace AYC-ECU.
INSPECTION PROCEDURE 5
AYC is inoperative.
Unable to start or accelerate on slippery road surfaces.
Probable cause
The hydraulic oil level is probably low, there is an oil leak, the hydraulic unit is defective,
or the torque transfer differential is defective.
Low hydraulic oil level

Oil leak

Defective hydraulic unit

Defective torque transfer differential
NOTE
This symptom is limited only when the diagnosis code is correct.
NG
Replace the hydraulic unit.
NG
Replace the torque transfer differential.
Check the trouble symptom.
NG
Replace AYC fluid.
OK
Correct
Check the trouble symptom.NO
Replace the torque transfer differential.
OK
Is foreign matter trapped in the hydrau-
lic line?YES
Repair
OK
Check the AYC for operation.
(Refer to P.27-34.)OKCheck the AYC fluid.
NG
Add hydraulic oil.
NG
Check hydraulic pressure..
(Refer to P.27-35.)NGBleed the system of air.
(Refer to P.27-34.)
Check the hydraulic oil level.NGCheck for oil leak.OK
Repair

REAR AXLE – Troubleshooting <AYC>27-26
Item No.Normal value Checking requirements Check item
46Steer sensor (ST-N)Steering wheel position
Ignition switch: ON
Neutral positionON
Ignition switch: ON
90 deg. turned
from neutral
positionOFF
47Steer sensor (ST-1)Steering wheel position: Turn slowly counterclock-
wise.
Ignition switch: ONON and OFF are
indicated alternate-
ly.
48Steer sensor (ST-2)Steering wheel position: Turn slowly clockwise.
Ignition switch: ONON and OFF are
indicated alternate-
ly.
50Stop lamp switchAccelerator pedal position
Ignition switch: ON
DepressedON
Ignition switch: ON
ReleasedOFF
56Pressure switchForced activation No.13 or
No.14 is being executed.Electric pump in
operationLow
Electric pump
not in operationHigh
59ABS monitorABS monitorON
ABS not in operationOFF

REAR AXLE – Troubleshooting <AYC>27-28
CHECK AT AYC-ECU TERMINALS
TERMINAL VOLTAGE LISTING

The voltage is to be measured across each terminal and ground terminal.

Fig. below shows the arrangement of the terminals.
Terminal
No.Check itemCheck requirementNormally
1Lateral acceleration sensorIgnition switch: ON2.4 – 2.6 V
(horizontal position)
2Longitudinal acceleration
sensor ground
Lateral acceleration sensor
groundAt all times0 V
3Longitudinal acceleration
sensorIgnition switch: ON2.4 – 2.6 V
(horizontal position)
4Steer sensor (ST-2)Engine: Idle speed
Turn steering wheel slowly.0 V ↔ approx. 3 V
flashing
5Steer sensor (ST-1)Engine: Idle speed
Turn steering wheel slowly.0 V ↔ approx. 3 V
flashing
6*1FR wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
7*1FL wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
8*1RR wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
9*1FL wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
10Diagnosis selection inputWhen MUT-II is connected1 V or less
When MUT-II is disconnectedSystem voltage
11Stop lamp switchIgnition switch:
ON
Stop lamp switch: ONSystem voltage
ON
Stop lamp switch: OFF1 V or less
12*1ABS monitorWhen ABS monitor is activatedSystem voltage
When ABS monitor is deactivated1 V or less

REAR AXLE – Troubleshooting <AYC>27-29
Terminal
No.Normally Check requirement Check item
17Steer sensor (ST-N)Engine:
Idle speed
Steering wheel: Neutral position0.5 V or less
Idle speed
Steering wheel: Turned 90 from
neutral position2.5 – 3.5 V
18TPSIgnition switch:
ON
Accelerator pedal: Fully closed0.3 – 1.0 V
ON
Accelerator pedal: Fully open4.5 – 5.0 V
23Diagnosis data input/outputWhen MUT-II is connectedSerial communica-
tion with MUT-II
When MUT-II is disconnected1 V or less
24Idle position switchIgnition switch:
ON
Accelerator pedal: Fully closed2 V or less
ON
Accelerator pedal: Fully open4.5 – 5.0 V
25Accumulator pressure
switchIgnition switch:
ONAccumulator internal pressure:
Low2 V or less
Accumulator internal pressure:
HighSystem voltage
26ECU groundAt all times0 V
31AYC-ECU power supplyIgnition switch: ONSystem voltage
Ignition switch: OFF0 V
35AYC motor relayIgnition switch:
ON
When motor is energizedSystem voltage
ON
When motor is deenergized2 V or less
36AYC warning lampIgnition switch:
ON
When lamp is OFFSystem voltage
ON
When lamp is ON2 V or less
37Directional control valve
(right)
Ignition switch:
ON
Right clutch: ONSystem voltage
(right)ON
Right clutch: OFF0 V
38Proportioning valveIgnition switch:
ONAYC-ON0 V to system volt-
age
AYC-OFF0 V
39ECU backup power supplyAt all timesSystem voltage
45Directional control valve
(left)
Ignition switch:
ON
Left clutch: ONSystem voltage
(left)ON
Left clutch: OFF0 V
46ECU groundAt all times0 V
NOTE
*1: Indicates the vehicles with ABS.